Splitting of the first heart sound is audible when the split interval is 50 milliseconds or higher. Auscultation is best performed at the tricuspid area to observe such splitting sounds. When the chestpiece is shifted to the apex, the mitral component of the split heart sound becomes louder. Markedly split first heart sounds is an auscultatory indication of premature ventricular contractions or right bundle branch block
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The patient's position is supine.
